The map above shows incidence of drug crime (darkening shades of green) against locations of nursery schools (red dots). As you can see, the Mayor need not worry about infant crackheads. This and thousands of other comparisons can be made over on MapTube London, a new site from UCL's Centre for Advanced Spatial Analysis. MapTube London allows you add your own maps of the capital, and compare data by overlaying different maps. The perfect......